Mauna Kea is Hawaiian for "white mountain". The volcano is over 14,000 feet in elevation and occasionally gets snowfall. You can drive up to the visitor center at 9,000 feet and have great views of Mauna Loa and the night sky as you peer through telescopes.
Stargazing programs are from 6:00 pm to 10:00 pm every night. Visitors are not allowed to the summit after dark. Mauna Kea is about an hour to 1 1/2 hours drive from Hilo. Be careful of sharp turns on the Saddle Road and remember to bring warm clothes.
Visit these other great sites:
Hawaii Volcanoes National Park
Official site from NPS.gov
Southernmost point in the U.S.
Panorama from Don Bain's Virtual Guidebooks
Canon Digital Learning Center
Learn to take great photos
Panoramio.com
Map your photos in Google Earth